101. B, Explanation: The most accurate assessment is most likely to be obtained with
the eye directly above both the scale of the measure and the mark on the item being measured; 102. A and B, Explanation: The radio produces heat (thermal energy), as a by-product, and sound waves (kinetic energy); it uses electrical energy but does not produce it; 103. B, C and D, Explanation: The chemicals in the fi rework will be trans- ferred into heat, light and sound which are thermal, electromagnetic and kinetic ener- gies; 104. Ice, Explanation: The stronger forces give the ice a defi nite shape; 105. A, Explanation: The attractive forces between the molecules forces a liquid into a spheri- cal shape, which has the smallest area for a given volume; 106. B, Explanation: The adhesive force between the water and glass is greatest in the narrow tube and the water will rise highest; this is called capillary rise; 107. and 108. B and A, Explanation: The meniscus of mercury is convex while the meniscus of water curves down- wards; 109. B, Explanation: The bar will expand as it is heated so the pins will be pushed away from the blocks; 110. Winter, Explanation: In the summer the wires will expand and so slacken; if this was a summer scene then, come the winter, the wires would break as they contracted with the cold; 111. A, Explanation: The thicker glass beaker is more likely to crack because the glass on the inside expands while the outside glass does not; 112. B, Explanation: When heated, brass expands more than iron so the strip will bend with the brass on the outside as it will become longer than the iron; 113. A, Explanation: Water is unusual in that it is most dense at 4°C; most other
liquids expand uniformly as they warm; 114. B, Explanation: Some water will rise up the tube as the air cools and contracts; this will cause the water level in the beaker to fall; 115. and 116. A and F, Explanation: Once the switch is closed the circuit will be complete and the light will come on and the heating element will warm. As the bime- tallic strip warms it will bend away from the contact point, breaking the circuit;
117. D, Explanation: The behaviour of a gas is described by Boyle’s law which states
Answers and explanations 247
highest boiling point, alcohol the lowest; 120. B, Explanation: A fl ow of air would occur from the cool sea to the warm land, making the fl ag fl y on the landside of the pole; 121. The shiny tin can, Explanation: The shiny can will refl ect much of the radi- ated heat from the sun while the mat black one will absorb most of the heat; 122. B, Explanation: In the northern hemisphere the most effective direction for the solar panel would be south facing; 123. C, Explanation: The direction of North is given and from this you can work out the other directions; 124. C, Explanation: The latent heat of fusion of water is 340,000 joules per kilogram. This is the amount of heat needed to change 1 kg of ice into water without changing the temperature; 125. B, Explanation: Mineral salts lower the melting point of water so the temperature of the salty water must be lower than 0°C; 126. C, Explanation: The pressure on the ice of the weighted
thin wire will melt the ice immediately below the wire. The wire will move downwards but the water above the wire will refreeze. So the block will remain unchanged as the wire slowly passes through; 127. C and D, Explanation: Impurities such as salt will cause the boiling point of the water to rise so the water will come off the boil, the temperature of the water will increase and it will come back to the boil; 128. B, Explanation: At sea level water boils at 100°C. When the pressure is lower, as it is at altitude, it will boil at a lower temperature; 129. B, Explanation: Weight is the force of gravity caused by the pull of the Earth. This effect is slightly greater at the poles so the weight would be slightly heavier; 130. B, Explanation: The beams in both A and B can bend; however, in the triangle a bend in one of the lengths would cause tension or compression in another part of the same, making it much more ridged; 131. C the least, B the most, Explanation: Both ice and oil fl oat on water so they are less dense; 132. Bottom, Explanation: Pressure increases with depth; 133. C, Explanation: Pressure acts in all directions but the pressure at the bottom of an object is greater than at the top (this results in an upward force);
134. A petrol, B ice, Explanation: Ice is denser than petrol so it will sink below the
petrol; 135. A, 970 mbar, Explanation: The atmospheric pressure is usually lower when we experience a weather system that brings rain; 136. B, Explanation: Friction acts between two objects when they are in contact and resists movement; 137. D, Explanation: Friction can only act where contact exists; all the other forces listed can act at a distance; 138. Between 4 and 5, Explanation: The vehicle accelerates quickly
electrodes and current would cause electrolysis and break the water down to hydro- gen and oxygen. The composition of water is H20, so for every oxygen molecule there
are two hydrogen. There would be therefore twice as much hydrogen produced as oxygen. Experience shows that the hydrogen would be produced at the negative elec- trode (the cathode); 151. Circuit 1 and table 1, circuit 2 and table 2, Explanation: The light comes in circuit 1 only when A and B are both closed. In circuit 2 the light comes on when either switch A or B is closed; 152. At no point, Explanation: Gamma rays are highly energized and, while reduced by a thin sheet of lead, are not completely stopped; 153. B, Explanation: Betaparticles are fast-moving negative electrons that pass through cloth, paper etc but are stopped by dense substances such as alumin- ium; 154. A, Explanation: Alpha particles are positively charged and relatively large and slow. They are stopped by most materials, including paper; 155. C, Explanation: A hydroelectric energy source relies on water turning a turbine which is then converted into electric energy by a dynamo; 156. Both A and B, Explanation: The downward acceleration of the balls would be the same; the horizontal acceleration of ball B does not affect this so they would hit the ground at the same moment; 157. Cannot tell, Explanation: If the tyres were infl ated to the same pressure then you could tell that B carried the greatest load but without this information you cannot tell; 158. All equal, Explanation: The pressure is consistent throughout the fl uid; 159. A, Explanation: The weight × distance in A is equal on both sides, all the others are unequal, so the seesaw would move.
IQ tests
160. C, Explanation: A spells humbug, B hullabaloo; 161. D, Explanation: The
sequence is the multiples of 8, 8 × 2 = 16, 8 × 3 = 24, 8 × 4 = 32 and so on; 162. E, Explanation: This is the name for one of the continents; all the others are types of fabric; 163. C, Explanation: Divide the middle number of each set by the fi rst number to get the sum on the right; 164. C, Explanation: Starting with 7 and going anticlock- wise add 1, then 2, then 3, then 4, eg 10 + 3 = 13 + 4 = 17; 165. B, Explanation: A spells quarter, C spells quarrel; 166. C, Explanation: This is a type of stool; the others are types of chair; 167. C, Explanation: The sequence is the multiples of 6 starting with 11 × 6 = 66; 168. E, Explanation: Multiply the previous sum by 2 and deduct successively 2, 3, 4, 5 etc. Eg 24 × 2 = 48 – 3 = 45, 45 × 2 = 90 – 4 = 86;
169. Primitive; 170. A, Explanation: This is the only country in the list that does not
include a letter ‘u’ in its English spelling; 171. D, Explanation: The sequence is taken from the multiples of 9 starting with 6 × 9 = 54; 172. C, Explanation: in rows 6 – 4 =
Answers and explanations 249
whale; all the others are types of bridge; 175. D, Explanation: The numbers in the right-hand set are 2 less than their corresponding numbers in the left-hand set;
176. D, Explanation: Divide the middle number by the number on the left to get the
right-hand number, eg 36 ÷ 6 = 6; 177. E, Explanation: The sequence is taken from the multiples of 7 beginning with 7 × 8 = 56; 178. pp, Explanation: Platypus, an egg- laying Australian mammal; 179. B, Explanation: This is a peninsula in northern Europe; the rest are geological periods; 180. C, Explanation: A spells matter, B grumpy and D greasy; 181. C, Explanation: Divide the middle number by the number on the left: 49 ÷ 7 = 7; 182. D, Explanation: Going clockwise add 3, then 4, then 5, then 6, eg 1 + 3 = 4 + 4 = 8; 183. AAA, Explanation: The word is Rastafarian, a religion that follows the teachings of Haile Selassie; 184. C, Explanation: Divide the middle number by the one on the left, eg 45 ÷ 9 = 5; 185. B, Explanation: Going anticlockwise, double the sum and deduct successively –1, –2, –3, –4, –5, eg 20 × 2 = 40 – 3 = 37; 186. A, Explanation: This is a type of fuel; the rest are types of energy; 187. B, Explanation: The numbers in the right-hand set are six higher than the corresponding number in the left-hand set; 188. duplicate; 189. D, Explanation: This is a group of musicians; the others are types of music; 190. EEE, Explanation: Engineer; 191. D, Explanation: Going anti- clockwise starting with the question mark the series is formed from the multiples of 12 beginning 3 × 12 = 36; 192. C, Explanation: This is the surname of a famous physicist; the rest are names of types of star; 193. A, Explanation: B spells defi ne, C decide and D deduce and educed; 194. C, Explanation: They are the fi rst fi ve whole cubed numbers (1×1×1, 2×2×2, 3×3×3 etc); 195. D, Explanation: This is an example of a name; all the others are types of name; 196. hydrangea; 197. E, Explanation: This is a relative of the rhinoceros; the rest are types of knot; 198. D, Explanation: Add the fi rst two numbers in each set and then divide the sum by 2 to get the third number. Eg 3 + 3 = 6 ÷ 2 = 3; 199. bb, Explanation: rhubarb; 200. E, Explanation: This is a large rodent from South America; all the others are types of monkey; 201. B, Explanation: The sum of the numbers in the same position of each set is 10; 202. E, Explanation: This is the fi rst name of a painter, Pablo Picasso; the rest are types of painting; 203. C, Explanation: The letters spell ‘lunacy’; 204. D, Explanation: The sum of each set of numbers is 16, 2 + 6 + 8 = 16; 205. outrageous; 206. A, Explanation: Granite is a type of rock, the others are types of mineral (rocks are made of miner-
Explanation: The letters spell minutiae, B spells dislike, C intend, indent and tinned and D assemble; 230. E, Explanation: A marrow is a vegetable; the others are types of cereal; 231. D, Explanation: Going clockwise, subtract the second number from the fi rst to get the next number in the series; 232. B, Explanation: This is a type of pea; all the others are types of bean; 233. rhombus, Explanation: A rhombus is a diamond- shaped fi gure; 234. C, Explanation: This is a fl at surface; all the others are types of shape.